What is the reason of large holes in Swiss cheese? Name the fungus used in ripening of Roquefort cheese.

Explanation

### Step-by-Step Solution:

1. **Understanding Swiss Cheese**: Swiss cheese is known for its characteristic holes, which are formed during the cheese-making process.

2. **Role of Bacteria**: The primary bacterium responsible for the ripening of Swiss cheese is **Propionibacterium shermani**. This bacterium plays a crucial role in the fermentation process.

3. **Gas Production**: During the fermentation process, **carbon dioxide (CO2)** is produced as a byproduct of the metabolism of the bacteria.

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